I have to have a diesel. I make biodiesel. It's enviro friendly, etc etc etc. Plus, the diesel engine is inherently more thermodynamically efficient. I have hunted around a lot to find a diesel that meets all the criteria, size, weight, max power around 25 hp, water cooled, electric start, parts are available, etc. I really like the Isuzu b/c of their very good durability. But this group has access to a lot of knowledge. Am I overlooking the ideal power plant?

But I would be open to suggestions if somebody knows of either a 4 cyl (less vibration) or some boxer configuration diesel (inherently balanced, no extra efficiency robbing "balance shafts") for lower center of gravity. Not too spendy would also be good. <3,000 bucks would be my price range.

"As an ex-silversmith, I'd love to be beating out a nice copper bottom for a car, but for the weight, aluminum gives even more heat transfer, and you can solder it easily with zinc based rod."

I totally believe you could easily solder aluminum. I'm not totally convinced it would be easy for me. In my (admittedly very limited) experience, conditions have to be imaculately perfect for that to work. I'd also be worried about long term galvanic problems if I stick copper tubing to aluminum plate, and/or I'm not crazy about aluminum tubing in an environment with a lot of vibration.

I would use a dune buggy and put the drive train from a Metro XFi in the back....keep the wt under 1000 lbs with me on it would be easy and with less wt comes better FE.

Why build one when someone already has one

They are around 5000 bucks and if you had a titled geo metro you could use that since the engine in it is a slightly smaller G10 motor, just swap your motor and vin number onto the buggy, add lights and you are set.

Then just add a big fan on the back and you have what is possibly my next project

Hayes Diversified Technologies originally said they would sell a civilian version of the diesel kawasaki once they met their obligations to the U.S. Marines. Never happened. The military buys every machine they build.

Sadly, the ideas I have are not allowed on the road as a licensed vehicle. But the reverse trike idea is one of the better ones, and have shown a lot of potential. Would be interested to see if a double trans option (a cvt + a geared manual) would perhaps allow for decent flat ground work from micro type engines (micro in this case being things 500cc and lower) I could see where hilly terrain would be a problem though. I believe there is a simple 1.0L diesel generator application that could allow for some interesting savings, having the cvt spin the final gearing, while the manual could allow for a range setup... parking, city block, back road, highway cruise... (just a strange idea) I did a conversion once of a pedal powered quad "bicycle" (four wheels, extra frame for the outriggers of the wheels) and added a used weedeater engine to it, but could not really get it quiet like I wanted (angry bumblebee on speed comes to mind)